Police are looking for a passenger who was in the same car as Auckland teen Sosiua Helotu Ula, who died after falling out of the vehicle in Porirua on Sunday.
Senior Sergeant Christiaan Barnard said he believed Ula, 19, fell out of a black Mercedes on Warspite Ave just before 4pm on Sunday.
He died in hospital on Tuesday night and police launched a homicide investigation.
Police had since seized the Mercedes but had not yet found the passenger who was believed to be in the car at the time Ula fell out.
The driver of the Mercedes, registration GPW495, was arrested and appeared in court charged with driving while disqualified and supplying methamphetamine.
Barnard said police were also looking for the driver of a silver Mazda RX8, seen at the Waitangirua shops just before 4pm on Sunday, which was then seen driving at speed in Warspite Ave behind the Mercedes.
"We believe the driver of this car has information that will assist police with the homicide investigation," he said.
"We're appealing for both the passenger in the Mercedes and the driver of the Mazda to come forward and speak with police, along with anyone who saw either of these two vehicles in the Waitangirua area on Sunday afternoon who has not yet spoken with us."
Call Wellington Police Crime Squad on (04) 381 2000 or anonymously call Crimestoppers on 0800 555 111 if you have information